Help: Long exposures at night

[andrew_gormley]

What should I set the white balance to when taking long exposure

(~10-20 secs) at night time. I was playing around, with the camera set

on a tripod facing a large dark hedge. I then "painted" the hedge with

a torch [or "flashlight" for the NthAmerica crowd ;) ]. Results

weren't bad, but in the dark areas that weren't "painted", lots of

artifacts came up - i.e. lots of green & blue etc speckling. <p>Any

ideas, tips, etc would be much appreciated.<p>Andrew

[beauh44]

Hi Andrew, If you shoot raw you can change white balance after the shot. Most regular (non LED) flashlights do well with a tungsten white balance setting; however the green and blue speckling you're seeing is probably just sensor noise and that won't change with white balance. You might try a program like NeatImage or Noise Ninja for the noise. Good luck!

[phule]

What camera?

[bwcombs]

First, make sure you have the ISO set to the lowest possible

setting. That will help eliminate some of the noise you are

seeing.

 

Secondly, if you have this feature on your camera, enable the

Long Exposure Noise Reduction setting. This kicks in when you

have long exposures, and controls the level of electronic noise

evident in this type of exposure.

 

White balance really has no relationship to the amount of noise

you are seeing in your images. White balance adjusts to the

different wavelengths of light from varying light sources. In fact,

experimenting with different WB settings on long exposures can

sometimes result in some nice abstract or surprising images.

 

As a rule, if I am exposing a night scene with city lights, and

flooding the foreground in flash, I will use an auto or daylight WB

setting. I usually shoot in RAW, so these can be adjusted as

needed when processing.

[andrew_gormley]

Thanks for response. Camera is a Canon IXUSii (not sure what it is called over in USA). Unfortunately doesn;t have a RAW setting, but I can change the ISO and Whitebalance. Not sure about "on-camera" noise reduction.

[andrew_gormley]

Just did a search and found that noise-reduction kicks in automatically on shutter speeds of >1.5secs. Seems as though part of the problem was that I had the ISO set to 400.

[phule]

That's the Canon SD100 for the US market.

 

The SD100 might not do a dark-frame subtraction after the exposure (there's no mention of it in the dpreview.com review) so you might just have to see what ISO50 gets you.

[phule]

Andrew,

 

You are right. It does do the dark frame subtraction. Sorry about that.

[jeffrey_freiberg]

the white balance has nothing to do with the noise.your iso might be set to high?i use a program called neat image.www.neatimage.com that will help also with the noise,i cant see the threads from here,but i saw one other gentleman give you very similar food for thought...you might also try rear curtan if your camera has it,as part of the different lightings...good luck jeff

[hugh_crawford1]

You may want to try putting a blue filter on the lens, that way you will get the blue channel up above the noise floor without blowing out the red channel. Here are some photos taken with a Canon G2 at 2:00 am with 10 - 20 second exposures. I did not use a filter on these, but have on others.

http://www.thoughtballoon.com/hugh/photos/index.htm

[jim_g.1]

To answer your question about the white balance issue. Keeping in mind that will do nothing to resolve the noise issues you are having. Use a white card (or grey card) illuminated with the light source you are using to paint. That will set your white balance as close as you can get it IMHO.

[andrew_gormley]

Thanks for all your replies. Much appreciated.<br>Cheers<br>Andrew<br>P.S. Nice photos Hugh!

[superia400_junkie]

Buy an Olympus OM1 film camera off an online auction for $50-75. Comes with MLU. I love mine.